Heat exchanger and arrangement of tubes therefor

Abstract: A heat exchanger is provided with a first tank (111) and a second tank (112). Heat transfer tubes (15) are disposed between the tanks and are connected to the tanks to place the tanks in fluid communication. Either of the tanks may be divided into chambers by a partition. The partition has at least one portion which is oriented to be angularly offset from the direction of an air flow passing through the heat exchanger. The orientation of the partition permits the heat transfer tubes to be connected to the tanks in an arrangement so that no portion of the air flow can pass through the heat exchanger without striking at least one of the heat transfer tubes.

Description: BACKGROUND OF THE INVENTION 1. Field Of The Invention This invention relates to a heat exchanger and, more particularly, to an arrangement for heat transfer tubes in the heat exchanger. 2. Description Of The Related Art A typical arrangement for closely packed heat transfer tubes in a heat exchanger is shown, for example, in U.S. Patent No. 4,235,281 issued to Fitch et al.. Referring to Figs. 1-3, another heat exchanger 10 comprises an upper tank 11, a lower tank 12, and a heat exchanger core 13 disposed between upper tank 11 and lower tank 12. Heat exchanger core 13 comprises a plurality of heat transfer tubes 15 spaced apart from each other and substantially parallel to one another. Upper tank 11 is divided into three chambers, such as first upper chamber 18, second upper chamber 19, and third upper chamber 20, by a first upper partition 11a and a second upper partition 11b. First upper partition 11a is perpendicular to a direction of air flow Q through heat exchanger core 13. Second upper partition 11b is parallel to air flow Q. First upper chamber 19 has the same capacity as third upper chamber 20. Lower tank 12 is divided into two chambers, such first lower chamber 21 and second lower chamber 22 by lower partition 12a. First upper chamber 18 and third upper chamber 20 are respectively provided with inlet 16 and outlet 17 which connect heat exchanger 10 to an air conditioning system (not shown), i.e. a vehicle air conditioning system. Each of the plurality of heat transfer tubes 15 is joined at its opposite ends to upper tank 11 and lower tank 12. A heat exchanger medium, a refrigerant for example, is introduced through inlet 16 into first upper chamber 18. The medium flows down through tubes 15 to first lower chamber 21 of lower tank 12. The medium then flows back up tubes 15 to second upper chamber 19. The medium then flows down tubes 15 to second lower chamber 22 and back up through tubes 15 to third upper chamber 20. The medium then exits the heat exchanger through outlet 17. Generally, heat transfer tubes 15 are designed to be closely arranged so that the air flow Q, which passes across tubes 15, will strike each of the plurality of tubes 15. Generally, heat transfer tubes 15 cannot be connected to upper and lower tanks 11, 12 in the areas of partition portions 11a, 11b, and 12a. Therefore, tubes 15 are generally not disposed between tanks 11 and 12 in these areas. This absence of tubes creates a first pathway A along lower partition 12a and extending between upper and lower tanks 11, 12. A second pathway B is also created along partition 11a and extending between upper and lower tanks 11, 12. First pathway A is generally box-shaped and extends from a first end portion 13a of heat exchanger core 13 to a second end portion 13b of core 13. First pathway A is parallel to the direction of air flow Q. Second pathway B is also generally box-shaped and extends from a first side 13c of core 13 to a second side 13d of core 13. Second pathway B is generally perpendicular to air flow Q. A volume of air flow, which passes through first pathway A, is generally greater than a volume of air flow which passes through the remaining space in heat exchanger core 13. Thus, a relatively large quantity of air can flow through heat exchanger 10 without exchanging heat with the medium flowing through the plurality of heat transfer tubes 15. As a result, the heat exchange efficiency of heat exchanger 10 is reduced. Further, when a known heat exchanger is used as an evaporator, an evaporative capacity of the refrigerant cooling circuit is increased and, thus, a flow velocity of the circulating refrigerant is increased within the cooling circuit As a result of the increased evaporative capacity and refrigerant flow velocity, refrigerant pressure tends to drop within the heat exchanger. A heat exchanger according to the preamble of claim 1 is known from US 5,226,490. In order to achieve a repetitive precision fit and to assure a positive braze seal between a header and a tank a pocket with shoulders is provided in a tank wall. SUMMARY OF THE INVENTION It is an object of the present invention to maximize the heat exchange efficiency of a heat exchanger by preventing air from flowing through a core of the heat exchanger without striking any of a plurality of heat transfer tubes of the core. It is another object of the present invention to provide a heat exchanger wherein a pressure loss of refrigerant circuit using the heat exchanger can be minimized. This object is solved by a heat exchanger according to claim 1. A technical advantage of the present invention is that when heat transfer tubes are connected between the first and second tanks, no pathway exists which extends through the entire core entirely in the direction of the air flow. Thus, air is prevented from passing through the core without striking any of the heat transfer tubes. Another technical advantage of the present invention is that when the heat exchanger is used as an evaporator, pressure losses of a refrigerant within the heat exchanger can be minimized by changing the shape of the partition to gradually increase the capacity of chamber within the tank This causes refrigerant expansion, which reduces flow velocity, thereby maintaining relatively high refrigerant pressure. Further objects, features, and other advantages of the present invention will be understood from the detailed description with reference to the appropriate figures. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a heat exchanger in accordance with the prior art. Fig. 2 is a side view of the heat exchanger of Fig. 1. Fig. 3 is a partial, cross-sectional view of the heat exchanger of Fig. 2 taken along line 3-3. Fig. 4 is a perspective view of a heat exchanger according to a first embodiment of the present invention. Fig. 5 is a partial, cross-sectional view of the heat of Fig. 4 taken along line 5-5. Fig. 6 is a partial, cross-sectional view of a heat exchanger according to a second embodiment of the present invention. Fig. 7 is a partial, cross-sectional view of a heat exchanger according to a third embodiment of the present invention. Fig. 8 is an enlarged, partial, cross-sectional view of the heat exchanger of Fig. 7. Fig. 9 is a perspective view of a heat exchanger according to a fourth embodiment of the present invention. Fig. 10 is a partial, cross-sectional view of the heat exchanger of Fig. 9 taken along line 10-10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments of the present invention are illustrated in Figs. 410, in which the same numerals are used to denote elements which correspond to similar elements depicted in Figs. 1-3. Figs. 1-3 depict a heat exchanger according to the prior art. A detailed explanation of several elements and characteristics of the prior art heat exchanger of Figs. 1-3 is provided above and is, therefore, omitted from this section. In several of the figures, an air flow Q is shown to represent a typical direction of an air flow which contacts the heat exchanger and thereafter flows through a core of the heat exchanger, thereby passing across the heat transfer tubes of the core. Figs. 4 and 5 illustrate a first embodiment of the present invention. A heat exchanger is provided with an upper tank 111 and a lower tank 112. Lower tank 112 comprises two plate portions, such as first lower plate portion 112a and second lower plate portion 112b. Lower tank 112 also comprises four side walls, such as first lower side wall 112c, second lower side wall 112d, third lower side wall 112e, and fourth lower side wall 112f. Preferably, plate portions 112a, 112b and side walls 112c, 112d, 112e, 112f form a substantially box-shaped tank. However, the tanks of heat exchanger 110 can be of a variety of shapes and still benefit from the present invention. Lower tank 112 includes a lower partition 113, which is preferably formed therein to be substantially perpendicular to both first lower plate portion 112a and second lower plate portion 112b. Lower partition 113 divides lower tank 112 into two chambers, such as first lower chamber 121 and second lower chamber 122. Further, lower partition 113 comprises a first portion 113a, which preferably extends from first lower side wall 112c. A second portion 113b preferably extends from an end of first portion 113a to a central region of lower tank 112. A third portion 113c of lower partition 113 extends from second portion 113b to third lower side wall 112e. First portion 113a and third portion 113c are preferably formed so that they are oriented substantially perpendicular to both first lower side wall 112c which is referred to as a second front face and third lower side wall 112e. Thus, first and third portions 113a and 113c generally lie in the direction of air flow Q. Thus, the second front face is arranged in a direction substantially perpendicular to the direction of air flow. Second portion 113b is preferably formed so that it is oriented substantially parallel to first lower side wall 112c and third lower side wall 112e. Thus, second portion 113b is angularly offset from the direction of air flow Q and is preferably substantially perpendicular to the direction of air flow Q. The configuration of lower partition 113 results in a first pathway C, a second pathway D, and a third pathway E through heat exchanger core 13 when heat transfer tubes 15 are disposed between and connected to first and second tanks 112, 113. Pathways C, D, and E correspond to portions 113a, 113b, and 113c, respectively. Second pathway D is preferably substantially perpendicular to the direction of air flow Q. The result of this configuration is the avoidance of a single pathway extending from first end portion 13a of core 13 to second end portion 13b of core 13, the entirety of which is parallel to the direction of air flow Q. Thus, no portion of air flow Q can pass through heat exchanger core 13 without striking any of the plurality of heat transfer tubes 15. This feature of the present invention is an advantage over the prior art which allows a portion of the air flow to pass through the heat exchanger core without striking any heat transfer tubes. The configuration shown in Figs. 4 and 5, therefore, improves the heat exchanging efficiency of heat exchanger 10 as compared with the prior art heat exchanger shown in Figs. 1-3. Further, when a known heat exchanger is used as an evaporator, an evaporative capacity of the refrigerant cooling circuit is increased and, thus, a flow velocity of the circulating refrigerant is increased within the cooling circuit. As a result of the increased evaporative capacity and refrigerant flow velocity, refrigerant pressure tends to drop within the heat exchanger. Nevertheless, in this embodiment, the capacity of chamber 122 can be gradually increased by changing the shape of partition 113 in tank 112. Therefore, as the refrigerant circulates through the heat exchanger, refrigerant expansion within chamber 122 causes lower refrigerant flow velocity and maintains higher refrigerant pressure. Fig. 6 illustrates a second embodiment of the present invention. Lower tank 112 has lower partition 213, which is preferably formed therein to be substantially perpendicular to both first lower plate portion 112a and second lower plate portion 112b. Lower partition 213 divides lower tank 112 into two chambers similar to the previous embodiment. Lower partition 213 preferably extends from first lower side wall 112c to third lower side wall 112e so that partition 213 is angularly offset from and integrally oblique to the direction of air flow Q. The configuration of lower partition 213 results in a pathway F in heat exchanger core 13 when heat transfer tubes 15 are disposed between and connected to first and second tanks 112, 113. Pathway F corresponds to partition 213. Pathway F is thus angularly offset from and integrally oblique to the direction of air flow Q. The result of this configuration is the avoidance of a single pathway extending from first end portion 13a of core 13 to second end portion 13b of core 13, the entirety of which is parallel to the direction of air flow Q. Thus, no portion of air flow Q can pass through heat exchanger core 13 without striking any of the plurality of heat transfer tubes 15. Other advantages and features of the embodiment depicted in Fig. 6 are similar to those described above in connection with the first embodiment. Figs. 7 and 8 illustrate a third embodiment of the present invention. Lower tank 112 includes lower partition 313, which is preferably formed therein to be substantially perpendicular to both first lower plate portion 112a and second lower plate portion 112b. Lower partition 313 divides lower tank 112 into two in a manner similar to the previous embodiments. Partition 313 preferably extends from first lower side wall 112c to third lower side wall 112e and is generally wave-shaped. Partition 313 has successively opposed cavities (e.g., at 313a and 313b). One of the plurality of heat transfer tubes 15 is preferably connected to lower tank 112 at each of the successively opposed cavities of partition 313 so that the opening of a tube 15 opens into each of the cavities. Thus, if lower partition 313 was projected into heat exchanger core 13, partition 313 would be oriented so as to weave back and forth between successive heat transfer tubes 15. Partition 313 generally follows the direction of air flow Q. However, because partition 313 is wave-shaped, its successively opposed cavities each define a portion of partition 313 which is angularly offset from the direction of air flow Q. Preferably, lower partition 313 has a thickness which is smaller than a pitch of the tube arrangement of core 13. The configuration of partition 313 preferably results in no pathway through core 13. Thus, no portion of air flow Q can pass through core 13 without striking any of tubes 15. Other features and advantages of this embodiment are similar to those described above. Also, it will be easily understood by those having ordinary skill in the pertinent art that the features and advantages achieved by the various partitions of the above-described embodiments can be achieved by the use of similar partitions in upper tank 111. Figs. 9 and 10 illustrate a fourth embodiment of the present invention. Upper tank 111 is divided into two chambers by an upper partition 114. Partition 114 is preferably substantially perpendicular to first upper plate portion 111a and second upper plate portion 111b. Further, partition 114 includes first portion 114a extending from a first upper side wall 111c, second portion 114b extending from an end of first portion 114a and joining first portion 114a with a third portion 113c. Third portion 113c preferably extends from second portion 114b to third upper side wall 111e. First portion 114a and third portion 113c are preferably substantially perpendicular to both first and third upper side wall 111c and 111e. Second portion 114b is preferably substantially parallel to both first and second upper side walls 111c and 111e. The first upper side wall 111c is referred to as a first front face. The first front face 111c is arranged in a direction substantially perpendicular to a direction of air flow. The configuration of upper partition 114 results in a first pathway G, a second pathway H, and a third pathway I through heat exchanger core 13 when heat transfer tubes 15 are disposed between and connected to first and second tanks 112, 113. Pathways G, H, and I correspond to portions 114a, 114b, and 114c, respectively. Second pathway H is preferably substantially perpendicular to the direction of air flow Q. The result of this configuration is the avoidance of a single pathway extending from first end portion 13a of core 13 to second end portion 13b of core 13, the entirety of which is in the direction of air flow Q. Thus, no portion of air flow Q can pass through heat exchanger core 13 without striking any of the plurality of heat transfer tubes 15. In these respects, this embodiment is similar to the first embodiment. In this embodiment however, lower tank 112 is not divided into chambers. Instead, lower tank 112 comprises a single chamber. Other features and advantages of this embodiment are similar to those already described above. It will be obvious to those possessing ordinary skill in the pertinent art that variations of the preferred invention can be easily made within the scope of the claims. For example, a partition in either tank can be made of a variety of shapes and still prevent air from flowing through the core without striking at least one heat transfer tube.

Claims: A heat exchanger exposed to an air flow which flows in a direction, said heat exchanger comprising: a first tank (111) having a first front face (111c); a second tank (112) having a second front face (112c) spaced apart from said first tank; said first and second front faces (111c, 112c) being arranged substantially perpendicular to a direction of air flow (Q); a plurality of heat transfer tubes (15) disposed between said first and second tanks, each of said plurality of heat transfer tubes (15) connected at one end to said first tank (111) and at the other end to said second tank (112); and a partition (113, 213, 313, 114) disposed within said first tank (111) to divide said first tank (111) into at least two chambers, characterised in that said partition (113, 213, 313, 114) has at least one portion which is angularly offset from the direction of the air flow, and wherein said partition (113, 213, 313, 114) permits said plurality of heat transfer tubes (15) to be connected to said first and second tanks in an arrangement so that no portion of the air flow (Q) can pass through the heat exchanger without striking at least one of said plurality of heat transfer tubes (15). The heat exchanger of claim 1 wherein said at least one portion (114c, 113b) of said partition (113, 114) is perpendicular to the direction of the air flow (Q). The heat exchanger of claim 1 wherein said partition (313) is integrally oblique to the direction of the air flow (Q). The heat exchanger of one of claims 1 to 3 wherein said partition (313) is formed to be wave-shaped and extends from a first end portion of said heat exchanger to a second end portion of said heat exchanger, generally in the direction of the air flow (Q). The heat exchanger of claim 4, said wave-shaped partition (313) having successively opposed cavities, wherein one of said plurality of heat transfer tubes (15) is connected to said first (111) and second (112) tanks at each successively opposed cavity of said wave-shaped partition.

Inventors: AKOKI HISAO, CHIBA TOMOHIRO, AKOKI, HISAO, CHIBA, TOMOHIRO, AKOKI, HISAO, C/O SANDEN CORPORATION, CHIBA, TOMOHIRO, C/O SANDEN CORPORATION
Applicants: SANDEN CORP, SANDEN CORPORATION
Application year: 1994
Main classification: F28F9
IPC codes: F28D1, F28F9, F28F3